The present invention disclosed herein relates to a wireless power transmission apparatus, and more particularly, to a wireless power transmission apparatus using ultrasound.
There are generally three ways of wirelessly transferring energy. One way is transferring power using electromagnetic induction, another way is transferring power using radio frequency (RF), and the other way is transferring power using ultrasound.
Power transmission apparatuses using electromagnetic induction each includes a charge parent generating charging power using an external power source and a power receiving module receiving the charging power through an electromagnetic induction phenomenon from the charge parent. The electromagnetic induction technology has great efficiency to be commercialized.
However, in the case of electromagnetic waves, transferred energy is rapidly reduced as being inversely proportional to a square of a distance. Accordingly, power transmission apparatuses using electromagnetic induction are limited to being used when a distance between the charge parent and the power receiving module is short such as several centimeters.
Power transmission apparatuses using RFs collect energy of RFs whose radio ranges are very long and supply power to electronic devices or sensors. RFs exist in the air and have very broad radio ranges. However, since RFs have low energy densities, energy amounts after energy conversion are small.
Power transmission apparatuses using ultrasound each includes a transmitter generating ultrasound and a receiver receiving the generated ultrasound. An ultrasound generation apparatus generates oscillation, a medium is oscillated by an interaction between the oscillation and the medium, and ultrasound is transferred through the oscillated medium. Recently, systems for charging batteries by using such ultrasound generation apparatuses have been disclosed.
Also, power transmission apparatuses using ultrasound may be used with various media such as water and human skin. However, as in the case of under water or human skin, when an ultrasound transmitter and an ultrasound receiver are separated from each other, efficiency of power transmission between the ultrasound transmitter and ultrasound receiver decreases.